In his first sit-down interview since the Republican ticket lost to President Barack Obama, 2012 vice presidential nominee Rep. Paul D. Ryan defended his party’s positions on trimming spending for myriad entitlement and safety net programs — steps that critics have called draconian but which he says are necessary.

“We’re not preaching austerity. We’re preaching growth and opportunity,” the House Budget Committee chairman told host David Gregory in a half-hour conversation on “Meet the Press.”

“If you get our fiscal ship fixed, you prevent austerity,” the Wisconsin lawmaker continued, adding that when opponents call deep spending cuts “savage,” it does “disservice to the quality of debate we’re trying to have.”

Cuts to the federal food stamp program are one area where Republicans have been unfairly criticized, Ryan said: “All we’re trying to say is, you have to be eligible for this program,” rather than be automatically enrolled through other programs. “We need to target these things to people who actually need them.”

He also disputed claims that the country’s economy is in good enough shape that dramatic spending reductions are not absolutely necessary.

“If we keep going down this path, we will have a debt crisis,” Ryan said. “It’s not if, it’s when. ... It’s not a Democratic thing or a Republican thing, it’s a math thing.”

Ryan, who said he will play a role in shaping legislative proposals to overhaul the current tax code with lower tax rates at its centerpiece, was also sharply critical of Democrats, particularly those in the Senate.

In addition to failing to pass a budget for the past four years, Senate Democrats have been unwilling to work with Republicans to find common ground on meaningful spending reductions, Ryan said. Their unwillingness, along with that of the Obama administration, will ultimately trigger the sequester that was part of the 2011 debt deal when the two-month postponement expires March 1, he added.

“I think the sequester is going to happen,” Ryan said of the roughly $85 billion in fiscal 2013 spending cuts scheduled to occur in March throughout government operations, especially those linked to the Defense Department. “We think these sequesters will happen because the Democrats have rejected our efforts to replace those cuts with others and have offered no alternatives.”

Although Ryan has been highly sought-after for political commentary and reflection on the future of his career and of his party since his running mate, Mitt Romney, lost to Obama in November, Ryan said he had been waiting to speak publicly until after the inauguration.

“I wanted to see what sort of president we were looking at here,” he explained.

He is not happy with the one he has seen, he said.

“All of [his] statements and comments lead me to believe he is thinking more of a political conquest than a political compromise,” Ryan said of Obama. “And that’s why we’re going to have to have a big debate this spring about how ... to save us from a debt crisis, how to grow our economy.

“Obama is more concerned with 2014 than moving to the middle,” Ryan continued. “He’s wants to move farther to the left.”